Marianne Matichuk is a Canadian politician who was elected mayor of Greater Sudbury, Ontario, in the 2010 municipal election. She made history as the city's first elected female mayor and only the second serving woman mayor. Grace Hartman had previously been appointed mayor following the death of Max Silverman in 1966.

An occupational health and safety consultant, first with the city and later with Vale's operations in the Sudbury area, Marianne Matichuk was virtually unknown before launching her mayoral campaign in September 2010. However, she quickly gained attention with a focused campaign in which she issued a series of daily press releases attacking aspects of incumbent mayor John Rodriguez's record. By the time Oraclepoll Research released its poll of voter intentions in the mayoral campaign on October 12, Matichuk was in second place with 31.5 percent support, behind Rodriguez but ahead of longtime city councillor Ted Callaghan.

She made few concrete campaign promises of her own; those she did make included doing a line-item review of the city's budget and permitting retail stores in the city to open on Boxing Day.

The mayoral candidacy of David Popescu, a perennial candidate in the Sudbury area who was convicted of hate speech after advocating the execution of homosexuals in the 2008 federal election campaign, also emerged as a minor issue when he was permitted to participate in a mayoral debate sponsored by the Greater Sudbury Chamber of Commerce. Matichuk publicly criticized the Chamber of Commerce for not excluding Popescu from the debate, while opposing candidate Derek Young called Matichuk's move a populist ploy that would both undermine the democratic process and distract from other issues in the debate. The Chamber of Commerce reiterated that its standing policy when sponsoring political debates was to invite all registered candidates regardless of their personal views. Popescu had already participated in other mayoral debates during the 2010 election campaign without incident, and none of the candidates for mayor, including Matichuk, opted to boycott the Chamber of Commerce debate over Popescu's inclusion.

On October 22, the final Friday before election day, Matichuk secured the endorsement of the Sudbury Star. The paper noted her lack of political experience and the highly negative tone of her campaign. In an earlier editorial, in fact, the paper had named her alongside Toronto mayoral candidate Rob Ford as an example of an apparent Tea Party mentality entering into Ontario's municipal elections. However, the paper argued that in public debates and other dealings with the city's media, she had shown herself to be a substantial and practical voice. Rodriguez also tried to portray Matichuk as a Tea Party sort of candidate, accusing her in one debate of basing her campaign on "Sarah Palin mathematics" and ultimately attributing his defeat to a "negative, American-style campaign."

One of the dominant issues in the election campaign was the status of the city's St. Joseph's Hospital. With the completion of the new Sudbury Regional Hospital facility, the closure of the St. Joseph's site was imminent. However, despite the city's longtime interest in acquiring the property due to its adjacency to Bell Park and Lake Ramsey, the Sisters of St. Joseph sold the site in 2010 to Panoramic Properties, a condominium developer from Niagara Falls. The campaign was subsequently marked by conflicting claims about how much notice the Sisters gave to city council, and how much time and money the city did or didn't have to prepare a counteroffer for the site. A community group, Save Bell Park, formed to lobby for the site's protection.

Less dramatically, most voters identified road maintenance and property taxes as their other key priorities in the election. For the first time since the 2000 election, notably, the municipal amalgamation of the Regional Municipality of Sudbury into the current city of Greater Sudbury, which took place in 2000, did not register as a prominent election issue.

The issue of retail store hours in the city also became an election issue when Marianne Matichuk supported allowing businesses to set their own hours without regulation from the city. If passed, this would include allowing stores in the city to open on Boxing Day for the first time. With labor unions being a prominent political force in the city, the issue of balancing the rights of retailers to set business hours against the rights of workers to holiday time at Christmas has been a persistent debate in Sudbury's municipal politics.

On the final Friday of the election campaign, the Sudbury Star endorsed Matichuk for the mayor's chair. The following day, the paper published an article headlined "City misled public about manager's dismissal", alleging that Rodriguez and the incumbent council had deliberately lied to the public about the resignation of Alan Stephen, the former manager of the city's infrastructure and emergency services division, in 2006. However, the incident described in the article was one in which the city appeared to simply have followed its legal obligation to maintain confidentiality around matters involving employee relations. The newspaper subsequently faced criticism for its portrayal of the story and for publishing the story only after it would be too late for Rodriguez or any other member of the city's staff to respond ahead of election day. In an interview on CBC Northern Ontario's Points North following the election, Sudbury Star managing editor Brian MacLeod stated that the paper had received the information in an anonymous brown envelope several days before the story went to print. The Ontario Provincial Police subsequently announced that they were conducting an investigation into the leak.

Although incumbent mayor John Rodriguez faced significant criticism of his first term as mayor, an Oraclepoll Research survey released on October 13, 2010, twelve days before the election, suggested that he remained in the lead with 41.6 percent of decided voters. However, this represented a drop of 10.2 percent from his winning margin in the 2006 election. Marianne Matichuk, a political neophyte who was virtually unknown before announcing her campaign in early September, was in second place with 31.5 percent support, while councillor Ted Callaghan had 22.7 percent support. All of the other candidates combined had a total of 4.1 percent support. Notably, the poll did not register a single decided voter for either Popescu or Ed Pokonzie.

A subsequent CTV Northern Ontario poll, released in the final week of the campaign, showed significant tightening of the race, with 32 percent support for Rodriguez, 28 percent for Matichuk, and 18 percent for Callaghan, with 21 percent undecided.

In the early months of the 2014 municipal election campaign, Matichuk's silence about her reelection plans became a provincewide story when Toronto Star journalist Robert Benzie reported on Twitter that sources within the Ontario Liberal Party were claiming that Premier Kathleen Wynne would appoint Matichuk as the party's candidate in the provincial electoral district of Sudbury for the 2014 provincial election. Both Wynne and Matichuk denied the reports;^[1][2] however, the speculation failed to die down because of Matichuk's continued lack of clarity about her plans, and the local Liberal riding association's inability to get a firm date commitment for its nomination meeting from the party's head office.^[3] The party finally nominated Andrew Olivier as its candidate on May 8.^[4]

In January 2015, Matichuk expressed interest in running as a Liberal candidate for the electoral district of Sudbury in the 2015 federal election.^[5] She lost the nomination to lawyer and media proprietor Paul Lefebvre on March 28.^[6]

As of 2023, Matichuk currently holds positions on several boards, including chair of Workplace Safety & Prevention Services Ontario,^[7] board director at CAA North & East Ontario, and past president of Business & Professional Women Greater Sudbury. She has also served as a past board member on the international board of the Canada Nevada Business Council, as well as the national governor on the Board of Canadian Registered Safety Professionals.

In 2023, Matichuk voiced her support for Bonnie Crombie's bid for leadership of the Ontario Liberal Party. She was present at every one of Crombie's events in Sudbury, affirming, "I worked with Bonnie when I was the first elected female Mayor of Sudbury and found her to be a true leader who is extremely intelligent, strategic, straight forward, caring and most of all, brings people together"

Marianne Matichuk defeated former NDP MP and incumbent Mayor John Rodriguez, as well as sitting city councillor Ted Callaghan.